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The Nervous System: Brain, Cranial Nerves, Autonomic Nervous System, and Special Senses

This chapter provides an introduction to the structure and functions of the brain, cranial nerves, autonomic nervous system, and special senses. It explores the four main parts of the brain, brainstem, diencephalon, cerebrum, and cerebellum, and their respective roles. It also discusses the autonomic nervous system and the 12 cranial nerves along with their functions. Lastly, it covers the sense of smell, taste, and other special senses.

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The Nervous System: Brain, Cranial Nerves, Autonomic Nervous System, and Special Senses

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  1. Chapter 11 The Nervous System The Brain, Cranial Nerves, Autonomic Nervous System, and the Special Senses

  2. Introduction • Brain is divided into four main parts • Brainstem: controls breathing, heartbeat rates and reactions to auditory and visual stimuli • Diencephalon: controls homeostasis • Cerebrum: controls intellectual processes and emotions • Cerebellum: maintains body posture and balance

  3. The Principal Parts of the Brain

  4. The Principal Parts of the Brain (cont’d.) • Main parts: brainstem, diencephalon, cerebrum, and cerebellum • Protection • Cranial bones • Meninges • Cerebrospinal fluid • Ventricles • Interventricular foramen

  5. The Principal Parts of the Brain (cont’d.)

  6. The Anatomy and Functions of the Brainstem

  7. The Anatomy and Functions of the Brainstem (cont’d.) • Medulla oblongata • Ascending and descending tracts • Connect spinal cord with the brain • Some tracts cross over in medulla • Reticular formation: controls consciousness • Reflex centers

  8. The Anatomy and Functions of the Brainstem (cont’d.) • Pons varolii • Connects spinal cord with brain • Connects parts of brain with each other • Helps control breathing

  9. The Anatomy and Functions of the Brainstem (cont’d.) • Midbrain • Ventral cerebral peduncles: convey impulses from cortex to pons and spinal cord • Dorsal tectum: reflex center • Controls movement of head and eyeball (visual stimuli) • Controls movement of head and trunk (auditory stimuli)

  10. The Anatomy and Functions of the Diencephalon

  11. The Anatomy and Functions of the Diencephalon (cont’d.) • Optic tracts • Mamillary bodies: memory and emotional responses • Thalamus • Relay station for sensory impulses • Interpretation center for pain, temperature, and touch • Epithalamus: contains pineal gland

  12. The Anatomy and Functions of the Diencephalon (cont’d.) • Hypothalamus: homeostasis • Controls and integrates autonomic nervous system • Receives sensory impulses from internal organs • Controls pituitary gland and links endocrine and nervous systems

  13. The Cerebrum: Structure and Function

  14. The Cerebrum: Structure and Function (cont’d.)

  15. The Cerebrum: Structure and Function (cont’d.) • Cerebral cortex: gray matter surface • Longitudinal fissure separates two hemispheres • Gyri: folds • Sulci: grooves • Corpus callosum: bridge connecting two hemispheres

  16. The Cerebrum: Structure and Function (cont’d.) • Surface of the cortex • Motor areas control muscular movements • Sensory areas interpret sensory impulses • Association areas process emotions and intellect

  17. The Cerebrum: Structure and Function (cont’d.) • Cerebral hemispheres • Frontal lobe: muscle movement, moods, aggression, smell, motivation • Parietal lobe: touch, pain, balance, taste, temperature • Temporal lobe: hearing, smell, memory, abstract thought, judgment • Occipital lobe: vision

  18. The Cerebrum: Structure and Function (cont’d.)

  19. The Cerebellum: Structure and Function

  20. The Cerebellum: Structure and Function (cont’d.) • Butterfly-shaped • Two partially separated hemispheres connected by vermis • Functions • Coordinating muscular movements • Maintaining posture • Maintaining balance

  21. The Autonomic Nervous System

  22. The Autonomic Nervous System (cont’d.) • Subdivision of efferent PNS • Functions without conscious effort • Regulates functions of internal organs • Assists in maintaining homeostasis • Helps deal with emergency situations

  23. The Autonomic Nervous System (cont’d.) • Sympathetic • Energy and stressful situations • Increases heartbeat and breathing rates • Neurotransmitters: acetylcholine and norepinephrine

  24. The Autonomic Nervous System (cont’d.) • Parasympathetic • Restores body to nonstressful state • Neurotransmitter: acetylcholine • Stimulates digestion, urination, and defecation

  25. The 12 Cranial Nerves and Their Functions

  26. The 12 Cranial Nerves and Their Functions (cont’d.) • (I) Olfactory: smell • (II) Optic: sight • (III) Oculomotor: movement of eyeball, constriction of pupil • (IV) Trochlear: movement of eyeball

  27. The 12 Cranial Nerves and Their Functions (cont’d.) • (V) Trigeminal: chewing, sensations in teeth • (VI) Abducens: movement of eyeball • (VII) Facial: facial expression, taste, tear and salivary glands • (VIII) Vestibulocochlear: equilibrium, hearing

  28. The 12 Cranial Nerves and Their Functions (cont’d.) • (IX) Glossopharyngeal: swallowing, taste, salivary glands • (X) Vagus: certain muscle movements, sensory impulses • (XI) Accessory: swallowing, head movement • (XII) Hypoglossal: swallowing, speech

  29. The Special Senses

  30. The Sense of Smell • Molecules in air dissolve in nasal mucus • Bipolar sensory neurons transfer chemical impulse • Olfactory bulbs receive impulse • Impulse sent to olfactory cortex • Odor variety dependent on brain interpretation

  31. The Sense of Smell

  32. The Sense of Taste • Taste buds on tongue, palate, and pharynx • Taste bud cell types • Exterior capsule: epithelial cells • Interior: taste cells • Taste depends on chemicals dissolved in saliva • Taste influenced by olfactory sensations

  33. The Sense of Taste

  34. The Sense of Sight • Eyes protected by eyelids and eyelashes • Tears • Lubricate the eyes • Contain bacteriolytic lysozyme enzyme • Contain salt and gamma globulin

  35. The Sense of Sight (cont’d.)

  36. The Sense of Sight (cont’d.)

  37. The Sense of Hearing and Equilibrium • Outer ear • Auricle: external, visible, flexible part • External auditory meatus • Lined with hair and ceruminous glands • Tympanic membrane: vibrates in response to sound

  38. The Sense of Hearing and Equilibrium

  39. The Sense of Hearing and Equilibrium

  40. The Sense of Hearing and Equilibrium (cont’d.) • Middle ear • Auditory ossicles: malleus, incus, and stapes • Openings: oval and round windows • Eustachian tube: equalizes pressure

  41. The Sense of Hearing and Equilibrium (cont’d.) • Inner ear • Cochlea: hearing • Equilibrium • Static: vestibule • Kinetic: semicircular canals

  42. Summary • Named the principal parts of the brain • Discussed the functions of the major parts of the brain • Named the 12 cranial nerves • Discussed the role of the autonomic nervous system and its divisions • Described the special senses and the organs involved

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